Food Biotechnology

Elective Subject

B.Tech. (Biotechnology) 7th Semester

Prepared by: Dr. A. K. Gupta (AEC, Agra)

Food Biotechnology B. Tech.

Dr. A. K. Gupta

1Food spoilage 1-15 Microbial Role in food spoilage

Unit 1Course

• Role of microbes in food spoilage

• Food preservation (Principles, Operations and production)

• New protein Foods-SCP

• Mushroom

• Food yeast

• Algal proteins

Food Spoilage• Around a quarter of the world’s food supply is lost to

spoilage by microbes and insects. • Over the years man has developed many ways of

preserving foods and today’s food technologists have refined the techniques and come up with new ones.

• spoilage is not necessarily a bad thing. It shows us that a food has not been made or kept in the best conditions, alerting us to the possible presence of pathogenic microbes.

• Decomposition returns the chemicals in food back to the environment, to be used again in the life cycles of Earth.

Examples of food spoilage

Role of microbes in food spoilage• Like us, microbes need food to stay alive. The foodstuffs

that keep us healthy also provide the ideal nutrients for the growth of microbes.

• Microbes are all around us – in the air, the soil, water and our bodies.

• Microbes can soon get into food and, if the conditions are right, multiply rapidly.

• Unfortunately, when certain microbes grow on food, it soon begins to smell nasty, look slimy, change colour, taste awful or even acquire a furry coating.

• The food ‘goes off’ – it is spoiled. Even though it may not harm us, it is inedible and must be thrown away. There is also a chance that pathogenic microbes are present along with the spoilers.

Microbes causing food spoilage

Three main types of microbes cause spoilageBacteria

• Single-celled microbes that reproduce by splitting in two.

• Each individual bacterium is capable of carrying out all of

the activities needed to metabolise and reproduce.

• There are more than 5,000 known species of bacteria, with

new ones constantly being discovered.

• Familiar species of bacteria include: E.coli, Salmonella,

Bacillus

Growth conditions for bacteria

• Bacteria prefer moist conditions and can live in a wide range of temperatures. Most cannot grow at low pH (i.e. in acid conditions).

• In the right conditions of warmth, acidity and moisture they can multiply very fast, producing millions of cells in a few hours. Some bacteria form spores which are resistant to drying and heating. When conditions become favorable again, they germinate and an active cell is released.

Salmonella bacteria have flagella which they use to move around.

The different shapes of bacteria.

Types of bacteria• Bacteria cells have four basic shapes: 1. spheres 2. rods 3. spirals 4. commas.• They can be found as single cells, in pairs, chains or clusters.• A bacterial cell has a wall which maintains its shape and protects it.

Some bacteria can move. • Usually they use flagella, which are like little corkscrews. • These rotate from the base like a ship’s propeller. • The flagella may be distributed randomly over the whole cell surface, in

groups or singly.• Some bacteria have numerous fringe-like projections called fimbriae

which enable them to stick to each other. • Other bacteria produce a sticky substance around the cell wall. This

provides protection and helps them to stick to substrates, as well as each other.

Fungi• Fungi are a large and diverse group of organisms.

Their main characteristics are: • Their cells have membrane-bound nuclei (we call

them eukaryotic) • They do not use photosynthesis • They form spores • They have rigid cell walls • Respiration takes place in bodies called mitochondria

in the cytoplasm.• Fungal cells have an elaborate arrangement of

internal membranes. Fungi can be divided into two broad groups: filamentous fungi (including moulds and mushrooms) and yeasts

• Fungi reproduce by sexual and asexual means.• Most produce spores which in some types are

borne on bodies called sporangia. • Both spores and sporangia vary widely in size

and form, depending on how they are spread – by wind, water, mechanical means or vectors.

• Macrofungi produce large fruiting bodies which are familiar to us as mushrooms and toadstools.

• These produce spores in huge numbers and disperse them into the environment. In favourable conditions, these spores germinate and produce hyphae.

Moulds • Moulds are filamentous (thread-like) fungi. A single

filament is called a hypha. The hyphae branch as they grow forming a network called a mycelium.

• Each hypha grows from the tip and divides repeatedly along its length. The hyphae penetrate their food source (usually dead, but sometimes living, plant and animal matter). They excrete enzymes which break down the complex organic molecules into simpler substances. The soluble nutrients pass through the cell wall and membrane, enabling the fungus to grow.

• In most moulds the hyphae are divided by cross walls called septa which help to make filaments rigid but also control nutrient flow.

• Moulds can grow in dry and acid conditions and can tolerate a wide range of temperatures. These fungi produce airborne spores.

• Examples of moulds are: Penicillium, Mucor, Aspergillus.

Potato blight is caused by a mould growing on the leaves of the plant.

Yeasts• These are microscopic.• single celled fungi that are usually round or oval in shape. • Most reproduce by budding. • When yeasts respire anaerobically they convert sugars into ethanol

and carbon dioxide by a process known as fermentation. • They are mainly used to make fermented foods such as beer, wine

or bread,.• The biochemical activities of yeasts can have unwanted effects in

some food products. Yeasts can tolerate dry and acid conditions.• Examples of yeasts include: Saccharomyces cerevisiae, Candida

Food Biotechnology B. Tech.Dr. A. K. Gupta

2

15-28Food preservation Principles

Pasteurization

• Pasteurization is a process which slows microbial growth in foods.

• The process was named after its creator, French chemist and microbiologist Louis Pasteur.

• The first pasteurization test was completed by Louis Pasteur and Claude Bernard on April 20, 1862.

• The process was originally conceived as a way of preventing wine and beer from souring.

Pasteurizer

Pasteurization Process

• Unlike sterilization, pasteurization is not intended to kill all pathogenic micro-organisms in the food or liquid.

• Instead, pasteurization aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurization product is refrigerated and consumed before its expiration date).

• Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product.

• Certain food products are processed to achieve the state of Commercial sterility.

• Pasteurization typically uses temperatures below boiling since at temperatures above the boiling point for milk, casein micelles will irreversibly aggregate (or "curdle").

• There are two main types of pasteurization used today: High Temperature/Short Time (HTST) and Extended Shelf Life (ESL) treatment.

• Ultra-high temperature (UHT or ultra-heat treated) is also used for milk treatment.

• In the HTST process, milk is forced between metal plates or through pipes heated on the outside by hot water, and is heated to 71.7 °C (161 °F) for 15-20 seconds.

• UHT processing holds the milk at a temperature of 138 °C (280 °F) for a fraction of a second. ESL milk has a microbial filtration step and lower temperatures than HTST.

• Milk simply labeled "pasteurization " is usually treated with the HTST method, whereas milk labeled "ultra-pasteurization " or simply "UHT" has been treated with the UHT method.

• The HTST pasteurization standard was designed to achieve a 5-log reduction, killing 99.999% of the number of viable micro-organisms in milk.

• This is considered adequate for destroying almost all yeasts, mold, and common spoilage bacteria and also to ensure adequate destruction of common pathogenic heat-resistant organisms (including Mycobacterium tuberculosis, which causes tuberculosis and Coxiella burnetii, which causes Q fever).

• HTST pasteurization processes must be designed so that the milk is heated evenly, and no part of the milk is subject to a shorter time or a lower temperature.

• Pasteurization is typically associated with milk, first suggested by Franz von Soxhlet in 1886. HTST pasteurized milk typically has a refrigerated shelf life of two to three weeks, whereas ultra pasteurized milk can last much longer when refrigerated, sometimes two to three months. When UHT treatment is combined with sterile handling and container technology (such as aseptic packaging), it can even be stored unrefrigerated for 3-4 months.[citation needed]

• In addition to the standard HTST and UHT standards, there are other lesser-known pasteurization techniques.

• The first technique, called "batch pasteurization“.

• It involves heating large batches of milk to a lower temperature, typically 63 °C (145 °F) for 30 minutes, followed by quick cooling to about 4 °C (39 °F).

• The other technique is called higher-heat/shorter time (HHST), and it lies somewhere between HTST and UHT in terms of time and temperature.

• Pasteurization causes some irreversible and some temporary denaturation of the proteins in milk.

• Milk pasteurization has been subject to increasing scrutiny in recent years, due to the discovery of pathogens that are both widespread and heat resistant (able to survive pasteurization in significant numbers).

• Researchers have developed more sensitive diagnostics, such as real-time PCR and improved culture methods that have enabled them to identify pathogens in pasteurized milk.

• Some of the diseases that pasteurization can prevent are tuberculosis, diphtheria, salmonella, strep throat, scarlet fever, listeriosis and typhoid fever.

Food Biotechnology B. Tech.

Dr. A. K. Gupta

3

Food Preservation 28-Food Preservation Operations

Flash Pasteurization• Flash pasteurization, also called "High Temperature

Short Time" processing.• It is a method of heat pasteurization of perishable

beverages like fruit and vegetable juices, beer, and dairy products.

• Compared to other pasteurization processes, it maintains color and flavor better.

• It is done prior to filling into containers in order to kill spoilage microorganisms, to make the products safer and extend their shelf life.

• The liquid moves in a controlled, continuous flow while subjected to temperatures of 71.5 °C (160 °F) to 74 °C (165 °F), for about 15 to 30 seconds, a ratio expressed as pasteurization units.

• Flash pasteurization is widely used for fruit juices. • Tropicana Products has used flash pasteurization since

the 1950s.

Food irradiation

• Food irradiatio is the process of exposing food to ionizing radiation to destroy microorganisms, bacteria, viruses, or insects that might be present in the food.

• Further applications include sprout inhibition, delay of ripening, increase of juice yield, and improvement of re-hydration.

• Irradiation is a more general term of deliberate exposure of materials to radiation to achieve a technical goal (in this context 'ionizing radiation' is implied).

• As such it is also used on non-food items, such as medical hardware, plastics, tubes for gas-pipelines, hoses for floor-heating, shrink-foils for food packaging, automobile parts, wires and cables (isolation), tires, and even gemstones.

• Compared to the amount of food irradiated, the volume of those every-day applications is huge but not noticed by the consumer.

• The genuine effect of processing food by ionizing radiation relates to damages to the DNA, the basic genetic information for life.

• Microorganisms can no longer proliferate and continue their malignant or pathogenic activities.

• Spoilage-causing micro-organisms cannot continue their activities. Insects do not survive or become incapable of proliferation. Plants cannot continue the natural ripening or aging process.

• The speciality of processing food by ionizing radiation is that the energy density per atomic transition is very high; it can cleave molecules and induce ionization (hence the name), which is not achieved by mere heating.

• This is the reason for both new effects and new concerns. The treatment of solid food by ionizing radiation can provide an effect similar to heat pasteurization of liquids, such as milk. However, the use of the term "cold pasteurization" to describe irradiated foods is controversial, since pasteurization and irradiation are fundamentally different processes.

• Food irradiation is currently permitted by over 40 countries and volumes are estimated to exceed 500,000 metric tons annually world wide.

Canning• In 1809, a French confectioner and brewer, Nicolas Appert,

observed that food cooked inside a jar did not spoil unless the seals leaked, and developed a method of sealing food in glass jars.

• The reason for lack of spoilage was unknown at the time, since it would be another 50 years before Louis Pasteur demonstrated the role of microbes in food spoilage. However, glass containers presented challenges for transportation.

• Glass jars were largely replaced in commercial canneries with cylindrical tin or wrought-iron canisters (later shortened to "cans") following the work of Peter Durand (1810).

• Cans are cheaper and quicker to make, and much less fragile than glass jars. Glass jars have remained popular for some high-value products and in home canning.

• Tin-openers were not invented for another thirty years — at first, soldiers had to cut the cans open with bayonets or smash them open with rocks.

Food Biotechnology B. Tech.

Dr. A. K. Gupta

4

Food Preservation 28-Food Preservation Operations

Food Canning ProcessCanning is a method of preserving food in which the food is processed and sealed in an airtight container.

• The packaging prevents microorganisms from entering and proliferating inside.

• To prevent the food from being spoiled before and during containment, quite a number of methods are used: pasteurization, boiling (and other applications of high temperature over a period of time), refrigeration, freezing, drying, vacuum treatment, antimicrobial agents that are natural to the recipe of the foodstuff being preserved, a sufficient dose of ionizing radiation, submersion in a strongly saline, acid, base, osmotically extreme (for example very sugary) or other microbe-challenging environments.

• From a public safety point of view, foods with low acidity (a pH more than 4.6) need sterilization under high temperature (116-130°C).

• Foods that must be pressure canned include most vegetables, meats, seafood, poultry, and dairy products.

• The only foods that may be safely canned in an ordinary boiling water bath are highly acidic ones with a pH below 4.6, such as fruits, pickled vegetables, or other foods to which acidic additives have been added.

• Modern double seams provide an airtight seal to the tin can. This airtight nature is crucial to keeping bacteria out of the can and keeping its contents sealed inside. Thus, double seamed cans are also known as Sanitary Cans. Developed in 1900 in Europe, this sort of can was made of the traditional cylindrical body made with tin plate. The two ends (lids) were attached using what is now called a double seam. A can thus sealed is impervious to the contamination by creating two tight continuous folds between the can’s cylindrical body and the lids. This eliminated the need for solder and allowed improvements in manufacturing speed, reducing cost.

• Double seaming uses rollers to shape the can, lid and the final double seam. To make a sanitary can and lid suitable for double seaming, manufacture begins with a sheet of coated tin plate. To create the can body rectangles are cut and curled around a die and welded together creating a cylinder with a side seam.

• Rollers are then used to flare out one or both ends of the cylinder to create a quarter circle flange around the circumference. Precision is required to ensure that the welded sides are perfectly aligned, as any misalignment will cause inconsistent flange shape, compromising its integrity.

• A circle is then cut from the sheet using a die cutter. The circle is shaped in a stamping press to create a downward countersink to fit snugly in to the can body. The result can be compared to an upside down and very flat top hat. The outer edge is then curled down and around approximately 140 degrees using rollers to create the end curl.

• The result is a steel tube with a flanged edge, and a countersunk steel disc with a curled edge. A rubber compound is put inside the curl.

Nutrition Value

• Canning is a way of processing food to extend its shelf life. The idea is to make food available and edible long after the processing time. Although canned foods are often assumed to be of low-nutritional value (due to heating processes or the addition of preservatives), some canned foods are nutritionally superior -- in some ways -- to their natural form. For instance, canned tomatoes have a higher, available lycopene content.

Food Biotechnology B. Tech.

Dr. A. K. Gupta

5

Food spoilage 1-15New Protein Foods

Single Cell Protein (SCP)• The dried cells of microorganisms (algae, bacteria,

actinomycetes and fungi) used as food or feed are collectively called microbial protein.

• Microorganisms which are allowed to grow on waste products from agro based industries produce a large amount of proteins and store them in their cell bodies. These organisms are called as single cell proteins.

• Number of microorganisms are the part of diet since ancient time.

• Fermented yeast (Sacchromyces sp.) recovered as aleavening agent for bread (2500 B.C.).

• The worldwide food protein deficiency is becoming alarming day to day. During World War II, when there were stortages in proteins and vitamins in the diet, the Germans produced yeasts and a mould (Geotrichum candidum) in some quantity   for food; this led to the idea to produce edible proteins on a large scale by means of microorganisms during 1970s.

• Several industrial giants investigated the possibility of converting cheap organic materials into protein using microorganism. Single-Cell Protein (SCP) is a term coined at Massachusetts Institute of Technology by Prof C.L. Wilson (1966) and represents microbial cells (primary) grown in mass culture and harvested for use as protein sources in foods or animal feeds. Many scientists believe that single-cell protein production are possible solution to meet out the shortage of protein.

Palatibility of mushroom was also recognized in Rome.

• Single cell protein has the potential to be developed into a very large source of supplemental protein that could be used in livestock feeding. In some regions single cell protein could become the principal protein source that is used for domestic livestock, depending upon the population growth and the availability of plant feed protein sources. This could develop because microbes can be used to ferment some of the vast amounts of waste materials, such as straws; wood and wood processing wastes; food, cannery and food processing wastes; and residues from alcohol production or from human and animal excreta. Producing and harvesting microbial proteins is not without costs, unfortunately. In nearly all instances where a high rate of production would be achieved, the single cell protein will be found in rather dilute solutions, usually less than 5 % solids. Methods available for concentrating include, filtration, precipitation, coagulation, centrifugation, and the use of semi-permeable membranes. These de-watering methods require equipment that is quite expensive and would not be suitable for most small-scale operations. Removal of the amount of water necessary to stabilize the material for storage, in most instances, is not currently economical. Single cell protein must be dried to about 10 % moisture, or condensed and acidified to prevent spoilage from occurring, or fed shortly after being produced. Caution: Microbial protein has a high nucleic acid content, so levels need to be limited in the diets of monogastric animals. Some organisms can also produce mycotoxins. Source: Single cell protein can be produced on a number of different substrates, often this is done to reduce the Biological Oxidation Demand of the effluent streams leaving various type of agricultural processing plants.

• Microbial protein term is replaced by single cell protein during the first international conference on microbial protein at MIT.

• Some actinomycetes and filamentous fungi were reported to produce protein from various substrates.

Advantages of producing SCP

• Rapid succession of generations

• High protein content

• Easily modifiable genetically

• Large no of raw materials can be used for the production of SCP

• Production in continuous culture

Food Biotechnology B. Tech.

Dr. A. K. Gupta

6

Protein Food 28-Mushroom

Mushroom

• A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus, hence the word mushroom is most often applied to those fungi (Basidiomycota, Agaricomycetes) that have a stem (stipe), a cap (pileus), and gills (lamellae, sing. lamella) on the underside of the cap, just as do store-bought white mushrooms.

• The word "mushroom" can also be used for a wide variety of gilled fungi, with or without stems, and the term is used even more generally, to describe both the fleshy fruiting bodies of some Ascomycota and the woody or leathery fruiting bodies of some Basidiomycota, depending upon the context of the word.

• Oyster mushroom (Pleurotus ostreatus) cultivated using artificial logs made from compacted sawdust in plastic containers, harvested early morning.

• The button mushroom (Agaricus bisporus), one of the most widely cultivated mushrooms in the world.

• Edible mushrooms are used extensively in cooking, in many cuisines (notably Chinese, European, and Japanese). Though mushrooms are commonly thought to have little nutritional value, many species are high in fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin, cobalamins, ascorbic acid. Though not normally a significant source of vitamin D, some mushrooms can become significant sources after exposure to ultraviolet light, though this also darkens their skin.[6] Mushrooms are also a source of some minerals, including iron, selenium, potassium and phosphorus.

• Most mushrooms that are sold in super markets have been commercially grown on mushroom farms. The most popular of these, Agaricus bisporus, is generally considered safe for most people to eat because it is grown in controlled, sterilized environments, though some individuals do not tolerate it well. Several varieties of A. bisporus are grown commercially, including whites, crimini, and portobello. Other cultivated species now available at many grocers include shiitake, maitake or hen-of-the-woods, oyster, and enoki.

• There are a number of species of mushroom that are poisonous, and although some resemble certain edible species, eating them could be fatal. Eating mushrooms gathered in the wild is risky and should not be undertaken by individuals not knowledgeable in mushroom identification, unless the individuals limit themselves to a relatively small number of good edible species that are visually distinctive. However even A. bisporus contains 'agaritine' which metabolises when eaten into hydrazine, which is carcinogenic, but this chemical is largely or completely removed by cooking.[7]

• More generally, and particularly with gilled mushrooms, separating edible from poisonous species requires meticulous attention to detail; there is no single trait by which all toxic mushrooms can be identified, nor one by which all edible mushrooms can be identified.

• Additionally, even edible mushrooms may produce an allergic reaction, from a mild asthmatic response to severe anaphylaxis shock.

• People who collect mushrooms for consumption are known as mycophagists, and the act of collecting them for such is known as mushroom hunting, or simply "Mushrooming".

• Medicinal mushrooms• Currently, many species of mushrooms, which have been used in Asian

folk medicine for thousands of years, are under intense study by ethnobotanists and medical researchers. Maitake, shiitake, Agaricus blazei, chaga, and reishi are prominent among those being researched for potential anti-cancer, anti-viral, and immunity-enhancing properties.

• In Europe and Japan, Polysaccharide-K (brand name Krestin), a chemical derived from Trametes versicolor, is an approved adjuvant for cancer therapy.[9][10] In China a clinical drug has been developed from Trametes versicolor, it is called PSP and serves a similar purpose as Polysaccharide-K. Some countries have not embraced these chemicals as drugs, believing they're power is over-stated. However, chemicals like Polysaccharide-K have well documented pharmaceutical value and are extremely safe with minimal side-effects.

• The shiitake mushroom has produced a clinical drug lentinan, for cancer treatment, which is approved in various countries including Japan.[11][12][13]

• Human clinical studies are currently being conducted in the United States to investigate potential anti-cancer properties of the common table mushroom. [14]

• Research has indicated certain mushrooms have anti-aromatase and anti-5-alpha reductase activity.

• Oyster mushrooms are a natural source of statin drugs, specifically, isomers of lovastatin[16].

• In 2009, a case-control study of the eating habits of 2,018 woman, revealed that women who consumed mushrooms had an approximately 50% lower incidence of breast cancer. Women who consumed mushrooms and green tea had a 90% lower incidence of breast cancer.[17]

• Psilocybin, a naturally occurring chemical in certain psychedelic mushrooms like Psilocybe cubensis, is being studied for its ability to help people suffering from psychological disorders, such as obsessive-compulsive disorder. Minute amounts have been reported to stop cluster and migraine headaches.

A double-blind study, done by the John Hopkins Hospital, showed that psychedelic mushrooms could provide people an experience with substantial personal meaning and spiritual significance.

In the study, one third of the subjects reported that ingestion of psychedelic mushrooms was the single most spiritually significant event of their lives.

Over two-thirds reported it among their five most meaningful and spiritually significant events.

• Mushrooms can be used for dyeing wool and other natural fibers. The chromophores of mushrooms are organic compounds and produce strong and vivid colors, and all colors of the spectrum can be achieved with mushroom dyes. Before the invention of synthetic dyes mushrooms were the source of many textile dyes.

• Some fungi, types of polypores loosely called mushrooms, have been used as fire starters (known as tinder fungi).

• Mushrooms and other fungi play a role in the development of effective biological remediation and filtration technologies. The US Patent and Trademark Office can be searched for patents related to the latest developments in mycoremediation and mycofiltration.

Psychoactive mushrooms• Psilocybin mushrooms possess psychedelic properties

.• They are commonly known as "magic mushrooms"

"mushies" or "shrooms" and are available in smart shops in many parts of the world, though some countries have outlawed their sale.

• Because of their psychoactive properties, some mushrooms have played a role in native medicine, where they have been used in an attempt to effect mental and physical healing, and to facilitate visionary states.

• One such ritual is the Velada ceremony. A practitioner of traditional mushroom use is the shaman and curandera (priest-healer).

• Psilocybin mushrooms are not the only psychoactive fungi. Amanita muscaria pictured above is also psychoactive.

• The active constituents are Ibotenic acid and Muscimol.

• The Muscaria chemotaxonomic group of Amanitas contain no amatoxins or phallotoxins, and are not hepatoxic.

• Some dry these in the sun to transform the Ibotenic acid into the more psychoactive Muscimol.

Questions

• 1  What are the main unit operations and their functions in anaerobic digestion?   What are five application of this process?

• 2  Compare the principles, advantages, and disadvantages of aerobic and anaerobic composting for treatment of the organic fraction of municipal solid waste.

• 3  What is the approach for bioremediation of toxic compounds in soil?

• 4 What are the sources and methods of mitigation of microorganism pollutants in indoor air (see Lecture 14 for more detailed information)?

• 5  What are the two major purposes of fermenting food?

• 6 What are the main unit operations and their functions in wastewater treat?   Give two examples of fermented milk, vegetables, fruits, breads, and meats.

Unit 2

• Fermentation as a method for preparing and preserving foods

• Food additives

• Coloring

• Flavoring

• Vitamins

Food Biotechnology B. Tech.

Dr. A. K. Gupta

1Fermentation 59-64 Fermntation as a method of preserving foods

2

Fermentation(as a method for preparing and preserving foods)

• Fermentation in food processing typically refers to the conversion of sugar to alcohol using yeast under anaerobic conditions.

• A more general definition of fermentation is the chemical conversion of carbohydrates into alcohols or acids.

• When fermentation stops prior to complete conversion of sugar to alcohol, a stuck fermentation is said to have occurred.

• The science of fermentation is known as zymology.

• Fermentation usually implies that the action of the microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer, and cider.

• Fermentation is also employed in preservation to create lactic acid in sour foods such as pickled cucumbers, kimchi and yogurt.

Fermentation: Historical Background• Fruits ferment naturally.• Fermentation precedes human history. Since

prehistoric times, however, humans have been controlling the fermentation process.

• The earliest evidence of winemaking dates from eight thousand years ago, in Georgia, in the Caucasus area.

• Seven-thousand-year-old jars containing the remains of wine have been excavated in the Zagros Mountains in Iran, which are now on display at the University of Pennsylvania.

•

• There is strong evidence that people were fermenting beverages in Babylon circa 5000 BC, ancient Egypt circa 3150 BC, pre-Hispanic Mexico circa 2000 BC, and Sudan circa 1500 BC.

• There is also evidence of leavened bread in ancient Egypt circa 1500 BC and of milk fermentation in Babylon circa 3000 BC.

• French chemist Louis Pasteur was the first known zymologist, when in 1854 he connected yeast to fermentation. Pasteur originally defined fermentation as "respiration without air". Pasteur performed careful research and concluded;

• The primary benefit of fermentation is the conversion of sugars and other carbohydrates, e.g., converting juice into wine, grains into beer, carbohydrates into carbon dioxide to leaven bread, and sugars in vegetables into preservative organic acids.

• Food fermentation has been said to serve five main purposes:[8]

• enrichment of the diet through development of a diversity of flavors, aromas, and textures in food substrates.

• preservation of substantial amounts of food through lactic acid, alcohol, acetic acid and alkaline fermentations.

• Biological enrichment of food substrates with protein, essential amino acids, essential fatty acids, and vitamins.

• Detoxification during food-fermentation processing.

• A decrease in cooking times and fuel requirements.

Food Biotechnology B. Tech.

Dr. A. K. Gupta

1

Fermentation 59-64 Fermntation as a method of preserving foods

• Fermentation has some uses exclusive to foods. Fermentation can produce important nutrients or eliminate antinutrients.

• Food can be preserved by fermentation, since fermentation uses up food energy and can make conditions unsuitable for undesirable microorganisms. For example, in pickling the acid produced by the dominant bacteria inhibit the growth of all other microorganisms. Depending on the type of fermentation, some products (e.g., fusel alcohol) can be harmful to people's health.

Stuck fermentation• A stuck fermentation is where a fermentation has

stopped before completion; i.e., before the anticipated percentage of sugars has been converted by yeast into alcohol or carbohydrates into carbon dioxide.

• Typically, a stuck fermentation may be caused by: – 1) insufficient or incomplete nutrients required to allow the

yeast to complete fermentation; – 2) low temperatures, or temperature changes which have

caused the yeast to stop working early; or – 3) a percentage of alcohol which has grown too high for the

particular yeast chosen for the fermentation.

• Corrections to stuck fermentations may include: 1) repitching a different yeast 2) incorporation of nutrients in conjunction with the repitched yeast; 3) restoration of accommodative temperatures for the given yeast.

Worldwide Fermented food utilization Pattern

• alcohol, wine, vinegar, olives, yogurt, bread, cheese • Asia

– East and Southeast Asia: amazake, asinan, bai-ming, belacan, burong mangga, com ruou, dalok, doenjang, douchi, jeruk, lambanog, kimchi , kombucha, leppet-so, narezushi, miang, miso, nata de coco, nata de pina, natto, naw-mai-dong, pak-siam-dong, paw-tsaynob in snow , prahok, ruou nep, sake, seokbakji, soy sauce, stinky tofu, szechwan cabbage , tai-tan tsoi, chiraki, tape, tempeh, totkal kimchi, yen tsai , zha cai

– Central Asia: kumis (mare milk), kefir, shubat (camel milk) – India: achar, appam, dosa, dhokla, dahi (yogurt), gundruk, idli,

mixed pickle • Africa: fermented millet porridge, garri, hibiscus seed, hot pepper sauce,

injera, lamoun makbouss, laxoox, mauoloh, msir, mslalla, oilseed, ogi, ogili, ogiri

• Americas: chicha, elderberry wine, kombucha, pickling (pickled vegetables), sauerkraut, lupin seed, oilseed, chocolate, vanilla, tabasco, tibicos

• Middle East: kushuk, lamoun makbouss, mekhalel, torshi, boza • Europe: rakfisk, sauerkraut, ogórek kiszony, surströmming, mead,

elderberry wine, salami, prosciutto, cultured milk products such as quark, kefir, filmjölk, crème fraîche, smetana, skyr.

• Oceania: poi, kaanga pirau (rotten corn), sago

Fermented foods Classification• Bean-based

miso, natto, soy sauce, stinky tofu, tempeh• Grain-based

Batter made from Rice and Lentil (Vigna mungo) prepared and fermented for baking Idlis and Dosas

• amazake, beer, bread, chouj, injera, makgeolli, murri, ogi, sake, sikhye, sourdough, rice wine, Malt whisky, grain whisky, Vodka, batter

• Vegetable-based• kimchi, mixed pickle, sauerkraut• Fruit-based• wine, vinegar, cider, brandy

• Honey-basedmead, metheglin

• Dairy-basedcheese, kefir, kumis (mare milk), shubat

(camel milk), cultured milk products such as quark, filmjölk, crème fraîche, smetana, skyr, yogurt

• Fish-basedbagoong, faseekh ,fish sauce, Hákarl, heshiko,

hidal khunda[verification needed], jeotgal, rakfisk, shrimp paste, surströmming

• Meat-basedsalami, prosciutto

Risks of consuming fermented foods

• Alaska, despite its small population, has witnessed a steady increase of cases of botulism since 1985. It has more cases of botulism than anywhere else in the United States of America.

• This is caused by the traditional Eskimo practice of allowing animal products such as whole fish, fish heads, walrus, sea lion and whale flippers, beaver tails, seal oil, birds, etc., to ferment for an extended period of time before being consumed. The risk is exacerbated when a plastic container is used for this purpose instead of the old-fashioned method, a grass-lined hole, as the botulinum bacteria thrive in the anaerobic conditions created by the plastic.

Food Additives

• Are substances added to food to preserve flavour or improve its taste and appearance.

• Some additives have been used for centuries; for example, preserving food by pickling (with vinegar), salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines.

• With the advent of processed foods in the second half of the 20th century, many more additives have been introduced, of both natural and artificial origin.

• To regulate these additives, and inform consumers, each additive is assigned a unique number.

• Initially these were the "E numbers" used in Europe for all approved additives.

• This numbering scheme has now been adopted and extended by the Codex Alimentarius Commission to internationally identify all additives, regardless of whether they are approved for use.

• E numbers are all prefixed by "E", but countries outside Europe use only the number, whether the additive is approved in Europe or not. For example, acetic acid is written as E260 on products sold in Europe, but is simply known as additive 260 in some countries.

• Additive 103, alkanet, is not approved for use in Europe so does not have an E number, although it is approved for use in Australia and New Zealand.

• Since 1987 Australia has had an approved system of labelling for additives in packaged foods. Each food additive has to be named or numbered. The numbers are the same as in Europe, but without the prefix 'E'.

• The United States Food and Drug Administration listed these items as "Generally recognized as safe" or GRAS and these are listed under both their Chemical Abstract Services number and FDA regulation listed under the US Code of Federal Regulations

Some food additives• Acids 

– Food acids are added to make flavors "sharper", and also act as preservatives and antioxidants. Common food acids include vinegar, citric acid, tartaric acid, malic acid, fumaric acid, lactic acid.

• Acidity regulators  – Acidity regulators are used to change or otherwise control the acidity and

alkalinity of foods. • Anticaking agents 

– Anticaking agents keep powders such as milk powder from caking or sticking.

• Antifoaming agents  – Antifoaming agents reduce or prevent foaming in foods.

• Antioxidants  – Antioxidants such as vitamin C act as preservatives by inhibiting the effects

of oxygen on food, and can be beneficial to health.

• Bulking agents  – Bulking agents such as starch are additives that increase the bulk

of a food without affecting its nutritional value. • Food coloring 

– Colorings are added to food to replace colors lost during preparation, or to make food look more attractive.

• Color retention agents  – In contrast to colorings, color retention agents are used to

preserve a food's existing color. • Emulsifiers 

– Emulsifiers allow water and oils to remain mixed together in an emulsion, as in mayonnaise, ice cream, and homogenized milk.

• Flavors  – Flavors are additives that give food a particular taste or smell, and

may be derived from natural ingredients or created artificially.

• Flavor enhancers  – Flavor enhancers enhance a food's existing flavors.

They may be extracted from natural sources (through distillation, solvent extraction, maceration, among other methods) or created artificially.

• Flour treatment agents  – Flour treatment agents are added to flour to improve

its color or its use in baking.

• Humectants  – Humectants prevent foods from drying out.

• Tracer gas – Tracer gas allow for package integrity testing to prevent foods from being

exposed to atmosphere, thus guaranteeing shelf life. • Preservatives 

– Preservatives prevent or inhibit spoilage of food due to fungi, bacteria and other microorganisms.

• Stabilizers  – Stabilizers, thickeners and gelling agents, like agar or pectin (used in jam

for example) give foods a firmer texture. While they are not true emulsifiers, they help to stabilize emulsions.

• Sweeteners  – Sweeteners are added to foods for flavoring. Sweeteners other than

sugar are added to keep the food energy (calories) low, or because they have beneficial effects for diabetes mellitus and tooth decay and diarrhea.

• Thickeners  – Thickeners are substances which, when added to the mixture, increase

its viscosity without substantially modifying its other properties.

• With the increasing use of processed foods since the 19th century, there has been a great increase in the use of food additives of varying levels of safety. This has led to legislation in many countries regulating their use.

• Boric acid was widely used as a food preservative from the 1870s to the 1920s, but was banned after World War I due to its toxicity, as demonstrated in animal and human studies.

• In the USA, this led to the adoption of the Delaney clause, an amendment to the Federal Food, Drug, and Cosmetic Act of 1938, stating that no carcinogenic substances may be used as food additives. However, after the banning of cyclamates in the USA and Britain in 1969, saccharin, the only remaining legal artificial sweetener at the time, was found to cause cancer in rats. Widespread public outcry in the USA, partly communicated to Congress by postage-paid postcards supplied in the packaging of sweetened soft drinks, led to the retention of saccharin despite its violation of the Delaney clause.

• In 2007, Food Standards Australia New Zealand published an official shoppers' guidance with which the concerns of food additives and their labeling are mediated [5].

• Cases like these highlight the controversy associated with the risks and benefits of food additives. Some artificial food additives have been linked with cancer, digestive problems, and neurological conditions such as ADD, or diseases like heart disease or obesity.[citation needed] Even "natural" additives may be harmful, whether because of overuse (for example table salt) or because of natural toxicity. An example is safrole, which was used to flavour root beer until it was shown to be carcinogenic. Due to the application of the Delaney clause, it may not be added to foods, even though it occurs naturally in sassafras and sweet basil.[6]

List of food additives as organized by the Codex Alimentarius Committee.

• The International Numbering System numbers below (INS #) are assigned by the committee to identify each food additive. The INS numbers generally correspond to E numbers for the same compound - e.g. INS 102, Tartrazine, is also E-102. INS numbers are not unique and in fact, one number may be assigned to a group of like compounds.

• On packaging in the European Union, approved food additives are written with a prefix of 'E'. Australia and New Zealand do not use a prefix letter when listing additives in the ingredients.

• In the table below, food additives approved for Europe are listed with an 'E'[citation needed], and those approved for Australia and New Zealand with an 'A' . See also the list of E numbers.

INS #       

Approvals       

Names     Type    

100 A E turmeric, curcumin colour (yellow and orange)

101 A E riboflavin (vitamin B2)

colour (yellow and orange)

102 A E tartrazine colour (yellow and orange) (FDA: FD&C Yellow #5)

103 A alkanet, chrysoine resorcinol

colour (red)

104 A E Quinoline Yellow WS

colour (yellow and orange) (FDA: D&C Yellow #10)

107 E Yellow 2G colour (yellow and orange)

110 A E Sunset Yellow FCF colour (yellow and orange) (FDA: FD&C Yellow #6)

111 ? E Orange GGN colour (orange)

120 A E Cochineal, carmines colour (red)

Food colour• The color of food is an integral part of our culture and

enjoyment of life. • Even early civilizations such as the Romans

recognized that people "eat with their eyes" as well as their palates.

• Saffron and other spices were often used to provide a rich yellow color to various foods. Butter has been colored yellow as far back as the 1300's.

• Today all food color additives are carefully regulated by federal authorities to ensure that foods are safe to eat and accurately labeled.

• Technically, a color additive is any dye, pigment or substance that can impart color when added or applied to a food, drug, cosmetic or to the human body.

• The Food and Drug Administration (FDA) is responsible for regulating all color additives used in the United States. All color additives permitted for use in foods are classified as "certifiable" or "exempt from certification“.

• Certifiable color additives are manmade, with each batch being tested by manufacturer and FDA. This "approval" process, known as color additive certification, assures the safety, quality, consistency and strength of the color additive prior to its use in foods.

• Color additives that are exempt from certification include pigments derived from natural sources such as vegetables, minerals or animals, and man-made counterparts of natural derivatives.

• Caramel color is produced commercially by heating sugar and other carbohydrates under strictly controlled conditions for use in sauces, gravies, soft drinks, baked goods and other foods.

• Whether a color additive is certifiable or exempt from certification has no bearing on its overall safety. Both types of color additives are subject to rigorous standards of safety prior to their approval for use in foods.

• Certifiable color additives are used widely because their coloring ability is more intense than most colors derived from natural products; thus, they are often added to foods in smaller quantities.

• Of nine certifiable colors approved for use in the United States, seven color additives are used in food manufacturing .

• Regulations known as Good Manufacturing Practices limit the amount of color added to foods. Too much color would make foods unattractive to consumers, in addition to increasing costs.

Why Are Color Additives Used In Foods?

• Color is an important property of foods that adds to our enjoyment of eating. Nature teaches is early to expect certain colors in certain foods, and our future acceptance of foods is highly dependent on meeting these expectations.

• Color variation in foods throughout the seasons and the effects of food processing and storage often require that manufacturers add color to certain foods to meet consumer expectations. The primary reasons of adding colors to foods include:

• To offset color loss due to exposure to light, air, extremes of temperature, moisture and storage conditions.

• To correct natural variations in color. Off-colored foods are often incorrectly associated with inferior quality. For example, some tree-ripened oranges are often sprayed with Citrus Red No.2 to correct the natural orangy-brown or mottled green color of their peels (Masking inferior quality, however, is an unacceptable use of colors.)

• To enhance colors that occur naturally but at levels weaker than those usually associated with a given food.

• To provide a colorful identity to foods that would otherwise be virtually colorless. Red colors provide a pleasant identity to strawberry ice while lime sherbet is known by its bright green color.

• To provide a colorful appearance to certain "fun foods." Many candies and holiday treats are colored to create a festive appearance.

• To protect flavors and vitamins that may be affected by sunlight during storage.

• To provide an appealing variety of wholesome and nutritious foods that meet consumers' demands.

How Are Color Additives Regulated?

• In 1900, there were about 80 man-made color additives available for use in foods. At that time there were no regulations regarding the purity and uses of these dyes.

• Legislation enacted since the turn of the century, however, has greatly improved food color additive safety and stimulated improvements in food color technology.

• The Food and Drug Act of 1906 permitted or "listed" seven man-made color additives for use in foods. The Act also established a voluntary certification program, which was administered by the U.S. Department of Agriculture (USDA); hence man-made color additives became known as "certifiable color additives".

• The Federal Food, Drug & Cosmetic (FD&C) Act of 1938 made food color additive certification mandatory and transferred the authority for its testing from USDA to FDA. To avoid confusing color additives used in food with those manufactured for other uses, three categories of certifiable color additives were created:

• Food, Drug and Cosmetic (FD&C) - Color additives with application in foods, drugs or cosmetics;

• Drug and Cosmetic (D&C) - Color additives with applications in drugs or cosmetics;

• In 1960, the Color Additive Amendments to the FD&C Act placed color additives on a "provisional" list and required further testing using up-to-date procedures.

• One section of the amendment known as the Delaney Clause, prohibits adding to any food substance that has been shown to cause cancer in animals or man regardless of the dose.

• Under the amendments, color additives exempt from certification also are required to meet rigorous safety standards prior to being permitted for use in foods.

• According to the Nutrition Labeling and Education Act of 1990, a certifiable color additive used in food must be listed in the ingredient statement by its common or usual name. All label printed after July 1, 1991 must comply with this requirement.

Table 1. Color Additives Permitted For Direct Addition To Human Food In The United States

Certifiable Colors

Colors Exempt from Certification

FD&C Blue No.1 (Dye and Lake), FD&C Blue No.2 (Dye and Lake), FD&C Green No.3 (Dye and Lake), FD&C Red No.3 (Dye), FD&C Red No.40 (Dye and Lake), FD&C Yellow No.5 (Dye and Lake), FD&C Yellow No.6 (Dye and Lake), Orange B*, Citrus Red No.2*

Annatto extract, B-Apo-8'-carotenal*, Beta-carotene, Beet powder, Canthaxanthin, Caramel color, Carrot oil, Cochineal extract (carmine); Cottonseed flour, toasted partially defatted, cooked; Ferrous gluconate *, Fruit juice, Grape color extract*, Grape skin extract* (enocianina), Paprika, Paprika oleoresin, Riboflavin, Saffron, Titanium dioxide*, Turmeric, Turmeric oleoresin, Vegetable juice

*These food color additives are restricted to specific uses.

Flavor• Flavor or flavour is the sensory impression of a food

or other substance, and is determined mainly by the chemical senses of taste and smell.

• The "trigeminal senses", which detect chemical irritants in the mouth and throat, may also occasionally determine flavor.

• The flavor of the food, as such, can be altered with natural or artificial flavorants, which affect these senses.

• Flavorant is defined as a substance that gives another substance flavor, altering the characteristics of the solute, causing it to become sweet, sour, tangy, etc.

• Of the three chemical senses, smell is the main determinant of a food item's flavor.

• While the taste of food is limited to sweet, sour, bitter, salty, and savory (umami) – the basic tastes – the smells of a food are potentially limitless.

• A food's flavor, therefore, can be easily altered by changing its smell while keeping its taste similar. Nowhere is this better exemplified than in artificially flavored jellies, soft drinks and candies, which, while made of bases with a similar taste, have dramatically different flavors due to the use of different scents or fragrances.

• The flavorings of commercially produced food products are typically created by flavorists.

Flavorants or flavorings• Flavorings are focused on altering or enhancing the

flavors of natural food product such as meats and vegetables, or creating flavor for food products that do not have the desired flavors such as candies and other snacks.

• Most types of flavorings are focused on scent and taste. Few commercial products exist to stimulate the trigeminal senses, since these are sharp, astringent, and typically unpleasant flavors.

• There are three principal types of flavorings used in foods, under definitions agreed in the E.U. and Australia: [1]

• Natural flavoring substances: Flavoring substances obtained from plant or animal raw materials, by physical, microbiological or enzymatic processes.

• They can be either used in their natural state or processed for human consumption, but cannot contain any nature-identical or artificial flavoring substances.

• Nature-identical flavoring substances: Flavoring substances that are obtained by synthesis or isolated through chemical processes, which are chemically identical to flavoring substances naturally present in products intended for human consumption. They cannot contain any artificial flavoring substances.

• Artificial flavoring substances: Flavoring substances not identified in a natural product intended for human consumption, whether or not the product is processed

Smell• Smell flavorants, or simply, flavorants, are engineered and

composed in similar ways as with industrial fragrances and fine perfumes.

• To produce natural flavors, the flavorant must first be extracted from the source substance. The methods of extraction can involve solvent extraction, distillation, or using force to squeeze it out.

• The extracts are then usually further purified and subsequently added to food products to flavor them. To begin producing artificial flavors, flavor manufacturers must either find out the individual naturally occurring aroma chemicals and mix them appropriately to produce a desired flavor or create a novel non-toxic artificial compound that gives a specific flavor.

• Most artificial flavors are specific and often complex mixtures of singular naturally occurring flavor compounds combined together to either imitate or enhance a natural flavor.

•

• These mixtures are formulated by flavorist to give a food product a unique flavor and to maintain flavor consistency between different product batches or after recipe changes.

• The list of known flavoring agents includes thousands of molecular compounds, and the flavor chemist (flavorist) can often mix these together to produce many of the common flavors. Many flavorants are esters.

• The compounds used to produce artificial flavors are almost identical to those that occur naturally, and a natural origin for a substance does not necessarily imply that it is safe to consume.

• In fact, artificial flavors are considered somewhat safer to consume than natural flavors due to the standards of purity and mixture consistency that are enforced either by the company or by law.

• Natural flavors in contrast may contain toxins from their sources while artificial flavors are typically more pure and are required to undergo more testing before being sold for consumption

• Flavors from food products are usually the result of a combination of natural flavors, which set up the basic smell profile of a food product while artificial flavors modify the smell to accent it.

Flavor creation• Most food and beverage companies do not create their own flavors

but instead employ the services of a flavor company.• Food and beverage companies may require flavors for new

products, product line extensions (e.g., low fat versions of existing products) or due to changes in formula or processing for existing products.

• The flavor creation is done by a specially trained scientist called a "flavorist.“

• The flavorist's job combines extensive scientific knowledge of the chemical palette with artistic creativity to develop new and distinctive flavors.

• The flavor creation begins when the flavorist receives a brief from the client.

• In the brief the client will attempt to communicate exactly what type of flavor they seek, in what application it will be used, and any special requirements (e.g., must be all natural).

• The communication barrier can be quite difficult to overcome since most people aren't experienced at describing flavors.

• The flavorist will use his or her knowledge of the available chemical ingredients to create a formula and compound it on an electronic balance.

• The Federal Food, Drug & Cosmetic (FD&C) Act of 1938 made food color additive certification mandatory and transferred the authority for its testing from USDA to FDA. To avoid confusing color additives used in food with those manufactured for other uses, three categories of certifiable color additives were created:

• Food, Drug and Cosmetic (FD&C) - Color additives with application in foods, drugs or cosmetics;

• Drug and Cosmetic (D&C) - Color additives with applications in drugs or cosmetics;

• The flavor will then be submitted to the client for testing. Several iterations, with feedback from the client, may be needed before the right flavor is found.

• Additional work may also be done by the flavor company. For example, the flavor company may conduct sensory taste tests to test consumer acceptance of a flavor before it is sent to the client or to further investigate the "sensory space.“

• The flavor company may also employ application specialists who work to ensure the flavor will work in the application for which it is intended.

• This may require special flavor delivery technologies that are used to protect the flavor during processing or cooking so that the flavor is only released when eaten by the end consumer.

Unit 3

• Organisms and their use for production of fermented foods and beverages

• Pickling• Alcoholic beverages• Cheese• Sourkrat• Idli• Vinegar

Food Biotechnology B. Tech.

Dr. A. K. Gupta

1Fermented foods

1-15 Cheese

Cheese• Cheese comes in many varieties. The variety determines the

ingredients, processing, and characteristics of the cheese. • The composition of many cheeses is defined by

Standards of Identity in the U.S. Code of Federal Regulations (CFR).

• Cheese can be made using pasteurized or raw milk.• Cheese made from raw milk imparts different flavors and

texture characteristics to the finished cheese.• For some cheese varieties, raw milk is given a mild heat

treatment (below pasteurization) prior to cheese making to destroy some of the spoilage organisms and provide better conditions for the cheese cultures.

• Cheese made from raw milk must be aged for at least 60 days, to reduce the possibility of exposure to disease causing microorganisms (pathogens) that may be present in the milk. For some varieties cheese must be aged longer than 60 days.

• Cheese can be broadly categorized as acid or rennet cheese, and natural or process cheeses.

• Acid cheeses are made by adding acid to the milk to cause the proteins to coagulate.

• Fresh cheeses, such as cream cheese or queso fresco, are made by direct acidification. Most types of cheese, such as cheddar or Swiss, use rennet (an enzyme) in addition to the starter cultures to coagulate the milk.

• The term “natural cheese” is an industry term referring to cheese that is made directly from milk.

• Process cheese is made using natural cheese plus other ingredients that are cooked together to change the textural and/or melting properties and increase shelf life.

•  

Ingredients

• The main ingredient in cheese is milk. • Cheese is made using cow, goat, sheep, water buffalo or a

blend of these milks.• The type of coagulant used depends on the type of cheese

desired. For acid cheeses, an acid source such as acetic acid (the acid in vinegar) or gluconodelta-lactone (a mild food acid) is used.

• For rennet cheeses, calf rennet or, more commonly, a rennet produced through microbial bioprocessing is used.

• Calcium chloride is sometimes added to the cheese to improve the coagulation properties of the milk.

• Flavorings may be added depending on the cheese. • Some common ingredients include herbs, spices, hot and

sweet peppers, horseradish, and port wine.•  

Worldwide, cheese is a major agricultural product. According to the Food and Agricultural Organization of the United Nations, over 18 million metric tons of cheese were produced worldwide in 2004. This is more than the yearly production of coffee beans, tea leaves, cocoa beans and tobacco combined. The largest producer of cheese is the United States, accounting for 30% of world production, followed by Germany and France.

Top cheese producers(1,000 metric tons)

 United States 4,275 (2006)

 Germany 1,927 (2008)

 France 1,884 (2008)

 Italy 1,149 (2008)

 Netherlands 732 (2008)

 Poland 594 (2008)

 Brazil 495 (2006)

 Egypt 462 (2006)

 Argentina 425 (2006)

 Australia 395 (2006)

Top cheese exporters (Whole Cow Milk only) - 2004(value in '000 US $)

 France 2,658,441

 Germany 2,416,973

 Netherlands 2,099,353

 Italy 1,253,580

 Denmark 1,122,761

 Australia 643,575

 New Zealand 631,963

 Belgium 567,590

 Ireland 445,240

 United Kingdom 374,156

Germany is the largest importer of cheese. The UK and Italy are the second- and third-largest importers

Top cheese consumers - 2003(kilograms per person per year)

 Greece 27.3

 France 24.0

 Italy 22.9

 Switzerland 20.6

 Germany 20.2

 Netherlands 19.9

 Austria 19.5

 Sweden 17.9

Bacterial Cultures • Cultures for cheese making are called lactic acid bacteria

(LAB) because their primary source of energy is the lactose in milk and their primary metabolic product is lactic acid.

• There is a wide variety of bacterial cultures available that provide distinct flavor and textural characteristics to cheeses.

• Starter cultures are used early in the cheese making process to assist with coagulation by lowering the pH prior to rennet addition.

• The metabolism of the starter cultures contribute desirable flavor compounds, and help prevent the growth of spoilage organisms and pathogens.

• Typical starter bacteria include Lactococcus lactis subsp. lactis or cremoris, Streptococcus salivarius subsp. thermophilus, Lactobacillus delbruckii subsp. bulgaricus, and Lactobacillus helveticus.

• Adjunct cultures are used to provide or enhance the characteristic flavors and textures of cheese. Common adjunct cultures added during manufacture include Lactobacillus casei and Lactobacillus plantarum for flavor in Cheddar cheese, or the use of Propionibacterium freudenreichii for eye formation in Swiss.

• Adjunct cultures can also be used as a smear for washing the outside of the formed cheese, such as the use of Brevibacterium linens of gruyere, brick and limburger cheeses.

• Yeasts and molds are used in some cheeses to provide the characteristic colors and flavors of some cheese varieties.

• Torula yeast is used in the smear for the ripening of brick and limberger cheese.

• Examples of molds include Penicillium camemberti in camembert and brie, and Penicillium roqueforti in blue cheeses.

•  

General Manufacturing Procedure

• The temperatures, times, and target pH for different steps, the sequence of processing steps, the use of salting or brining, block formation, and aging vary considerably between cheese types.

• The following flow chart provides a very general outline of cheese making steps.

• The general processing steps for Cheddar cheese are used for illustration.

General Cheese Processing Steps

Standardize MilkPasteurize/Heat Treat Milk

Cool Milk Inoculate with Starter & Non-Starter Bacteria and Ripen

Add Rennet and Form CurdCut Curd and Heat

Drain WheyTexture Curd

Dry Salt or BrineForm Cheese into Blocks

Store and AgePackage

Processing Steps in Cheddar Cheese Production

• The times, temperatures, and target pH values used for cheddar cheese will depend on individual formulations and the intended end use of the cheese. These conditions can be adjusted to optimize the properties of Cheddar cheese for shredding, melting, or for cheese that is meant to be aged for several years.

• 1. Standardize Milk • Milk is often standardized before cheese making to optimize the protein to fat ratio to make a

good quality cheese with a high yield

• 2. Pasteurize/Heat Treat Milk • Depending on the desired cheese, the milk may be pasteurized or mildly heat-treated to reduce

the number of spoilage organisms and improve the environment for the starter cultures to grow. Some varieties of milk are made from raw milk so they are not pasteurized or heat-treated. Raw milk cheeses must be aged for at least 60 days to reduce the possibility of exposure to disease causing microorganisms (pathogens) that may be present in the milk.

• 3. Cool Milk • Milk is cooled after pasteurization or heat treatment to 90°F (32°C) to bring it to the temperature

needed for the starter bacteria to grow. If raw milk is used the milk must be heated to 90°F (32°C).

• 4. Inoculate with Starter & Non-Starter Bacteria and Ripen• The starter cultures and any non-starter adjunct bacteria are added to the milk and held at 90°F

(32°C) for 30 minutes to ripen. The ripening step allows the bacteria to grow and begin fermentation, which lowers the pH and develops the flavor of the cheese.

• 5. Add Rennet and Form Curd • The rennet is the enzyme that acts on the milk proteins to form the curd.

After the rennet is added, the curd is not disturbed for approximately 30 minutes so a firm coagulum forms.

• 6. Cut Curd and Heat • The curd is allowed to ferment until it reaches pH 6.4. The curd is then cut

with cheese knives into small pieces and heated to 100°F (38°C). The heating step helps to separate the whey from the curd.

• 7. Drain whey • The whey is drained from the vat and the curd forms a mat.

• 8. Texture curd • The curd mats are cut into sections and piled on top of each other and

flipped periodically. This step is called cheddaring. Cheddaring helps to expel more whey, allows the fermentation to continue until a pH of 5.1 to 5.5 is reached, and allows the mats to "knit" together and form a tighter matted structure. The curd mats are then milled (cut) into smaller pieces.

• 9. Dry Salt or Brine • For cheddar cheese, the smaller, milled curd pieces are put back in

the vat and salted by sprinkling dry salt on the curd and mixing in the salt. In some cheese varieties, such as mozzarella, the curd is formed into loaves and then the loaves are placed in a brine (salt water solution).

• 10. Form Cheese into Blocks • The salted curd pieces are placed in cheese hoops and pressed into

blocks to form the cheese. • 11. Store and Age

• The cheese is stored in coolers until the desired age is reached. Depending on the variety, cheese can be aged from several months to several years.

• 12. Package• Cheese may be cut and packaged into blocks or it may be waxed. •